Hundreds of thousands of children could be left without health insurance due to an oversight in the Affordable Care Act.

Obamacare caps the cost of affordable coverage at no more than 9.5 percent of family income. Individuals with employer-provided coverage and their families cannot get subsidized coverage through state health exchanges, USA Today reports.

But due to an oversight, the section of the healthcare law dealing with employer-mandated coverage only applies to the employee. If a company chooses not to offer family benefits, millions of children and families would be forced into the exchanges but would be ineligible for subsidies.

By one estimate, 500,000 children could be affected, USA Today reports.

The alternative, which is to purchase a plan privately, might be a financial impossibility since it costs an average of $15,700 per year, according to a Kaiser Family Foundation estimate.

"We saw this 2½ years ago and thought, 'Has anyone else noticed this?'" Kosali Simon, a professor of public affairs at Indiana University who specializes in health economics, told USA Today. "Everyone said, 'No, no. You must be wrong.' But we weren't, and that's going to leave a lot of people out."

"The family glitch is definitely a drafting error that Congress made that needs to be fixed," Joan Alker, executive director of the Georgetown University Center for Children and Families, told USA Today. "But that seems unlikely."

Other glitches in the law may hurt families as well.

For example, there are cases where parents may be ineligible for government healthcare subsidies, but they may be unaware that their children may qualify for programs such as the Children's Health Insurance Program. In other cases, undocumented immigrants may be ineligible for subsidized insurance but their children would be.

In another scenario, veterans get individual benefits through the Department of Veterans Affairs, but not family coverage. Their families might be unaware they could get subsidized insurance through the exchange.

Children who live with grandparents receiving Medicare might be eligible.

By Jan. 1, virtually all Americans will be required to carry health insurance — through an employer, a government program, or on their own — or pay a penalty.

Meanwhile, the healthcare law is expected to produce other unintended consequences for families.

Hundreds of thousands of children could be left without health insurance due to an oversight in the Affordable Care Act. Obamacare caps the cost of affordable coverage at no more than 9.5 percent of family income.